The present invention relates to the detection of the Human Immunodeficiency Virus (HIV) in serum, plasma or other body fluids. In particular, this invention describes diagnostic assays which employ F(ab').sub.2 fragments as a probe for the detection of HIV 1 antigens.
HIV 1 is believed to be the causative agent in acquired immunodeficiency syndrome (AIDS) [Chamberland et al., Ann. Int. Med. (1984) 101:617-623; Seligman et al., New Eng. J. Med. (1984) 311:1286-1292]. The virus has been isolated from patients with AIDS and AIDS-related complex (ARC) as well as from healthy persons at high risk for AIDS (Gallo et al., Science (1984) 244:500-502).
Since Dec. 1986, enzyme immunoassays, for example, the Abbott HIV 1 Antigen assay (Abbott Laboratories, North Chicago, Illinois), have been commercially available on a research basis for detection of HIV 1 antigens. These tests are highly sensitive and provide a direct indication of the presence of the virus. Consequently, detection of HIV 1 antigens may be useful as an aid in the diagnosis and monitoring of HIV 1 infection (Pedersen et al., Brit. Med. J. (1987) 295:567-569; DeWolf et al., Brit. Med. J. (1987) 295:569-572).
The sensitivities of the current HIV 1 antigen assays are quite good, however, the specificity varies widely. All manufacturers appear to have samples which nonspecifically react with components of the assay yielding false reactives. For this reason, Abbott provides a confirmatory procedure which involves neutralization of HIV 1 antigen in the sample prior to assaying. Although this increases specificity to near 100%, the cost involved in additional testing warrants efforts to increase the predictive value of antigen testing. The invention described herein provides one method of significantly increasing specificity while also enhancing assay sensitivity and timing.